This invention relates generally to sheet and tape structures coated on one surface thereof with a pressure-sensitive or tacky adhesive (hereinafter referred to as an adhesive sheet) and more particularly to an adhesive sheet which has printability and is not provided with a strip-off type backing sheet and to a process for producing the same. This roll is hereinafter referred to in some cases as an adhesive label roll.
An adhesive label roll comprises, essentially, a base sheet layer (ordinarily of paper) having one surface possessing printability and a layer of a pressure-sensitive adhesive or tacky material provided laminately on the opposite surface of the base sheet layer and is wound into the form of a roll, that is, in a state where the laminated layers have been rolled up with the printable surface on the outer side, which is desirable from the viewpoint of use or preservation. In a roll of this character, the exposed surface of the printable base material layer inevitably faces and contacts the layer of the tacky adhesive material. Consequently, when the adhesive label sheet is to be unrolled by pulling from the roll, it unrolls with difficulty, or tearing of the paper or stripping between the paper layers thereof occurs, and clean and easy unrolling cannot be accomplished.
Accordingly, in adhesive label rolls known heretofore, strip-off paper is used as a base or backing paper. That is, in order to prevent the outer surface of the printable base material from directly contacting the confronting tacky adhesive layer, the roll is wound with a non-tacky strip-off sheet such as paper coated with a silicone resin interposed between the roll layers.
In an adhesive label roll of known character wherein strip-off paper is used, the roll diameter becomes large and, accordingly, the weight of the roll becomes large, whereby the handling thereof becomes inconvenient. Furthermore, since the material cost of the strip-off paper in some cases exceeds one half of that of the adhesive label roll, the use of strip-off paper gives rise to a problem also from the viewpoint of economy.
While it may appear to be possible to solve these problems by rendering non-tacky the exposed surface of the printable base layer by a processing such as coating with a silicone resin, for example, instead of providng an independent non-tacky layer (strip-off layer), the surface loses its capability of accepting printing ink in this case because of the water-repellent and oil-repellent nature of the silicone resin, whereby the printability of the surface is lost.